This invention relates to an inexpensive charging system whereby rechargeable cells of different physical size and/or electrical characteristics are selectively and alternatively connectible to a charge current source for recharging.
There is an ever increasing number of consumer products on the market today which are capable of being operated by rechargeable cells such as nickel-cadmium cells. These products use cells having a plurality of physical sizes and electrical characteristics. Three of the most common sizes of nickel-cadmium cells used today are the AA, C and D sizes.
In the case of certain lines of nickel-cadmium cells, such as manufactured by the General Electric Company, the assignee of the invention herein, the electrical characteristics of the C and D size cells are the same, while the electrical characteristics of the AA size cells are different from that of the C and D sizes. The characteristics of these cells are summarized below.
______________________________________ Recommended Charge Current Size Voltage Capacity (Charge Rate C/10) ______________________________________ AA 1.2V .5 Ah. 50 mA. C 1.2V 1 Ah. 100 mA. D 1.2V 1 Ah. 100 mA. ______________________________________
The variety of cell types in wide use in the consumer market has given rise to the need to provide a unitary charging device to accommodate the various cell types. One such device is described in U.S. Pat. No. 3,579,075 issued on May 18, 1971 and assigned to the assignee of the invention herein. While this device provides a viable approach for charging cells of a variety of types, it has failed to achieve widespread adoption in the consumer market because of its complexity and cost of construction.
Another such device is described in U.S. Pat. No. 4,009,429. This device also requires relatively high assembly costs for various reasons. One particular problem with the device of U.S. Pat. No. 4,009,429 is that it utilizes conductive coil springs which function as an electrical contact to the cell as well as providing the cell with a tight resilient fit within the compartment of the device. The construction of the springs mounted on the wall of the device with an eyelet is difficult and expensive to manufacture.
The features and designs for charging systems described in the foregoing U.S. Pat. Nos. 3,579,075 and 4,009,429 are incorporated herein by reference.
Accordingly, it is an object of this invention to provide an improved system for accommodating a plurality of cell types.
Another object of this invention is to provide a charging system for a plurality of cell types which is safe, relatively inexpensive to manufacture and simple to operate.